A recent increase in audio-visual oriented applications has led to a desire for the development of a TV receiver that can obtain higher resolution images. In order to satisfy the desire in turn, a Hi-vision TV receiver was developed. The Hi-vision TV receiver uses 1125 scanning lines, which are at least twice the number of the scanning lines used in an NTSC-system receiver of 525. Also, the Hi-vision receiver has an aspect ratio of 9:16 as compared to the NTSC-system receiver's aspect ratio of 3:4. As such, the Hi-vision receiver can display an image with higher resolution and realism than the NTSC-system one.
Although the Hi-vision system has these excellent features, the Hi-vision receiver cannot display a Hi-vision image even when an NTSC-system video signal is supplied as it is. The reason is that, as mentioned above, the NTSC system and the Hi-vision system have different standards.
To display the Hi-vision image corresponding to the NTSC-system video signal, the applicant of this application previously proposed a converter for converting the NTSC-system video signal into the Hi-vision video signal (see Japanese Patent Application No. Hei 6-205934). From an NTSC-system video signal, this converter extracts pixel data sets of a block (region) of the NTSC-system video signal, which correspond to an objective pixel in Hi-vision video signal, thereby deciding a class including the objective pixel based on level distribution patterns of the pixel data sets in this block and then producing the pixel data set of the above objective pixel corresponding to this class.
Also, the applicant of this application suggested a converter for converting a composite signal into a component signal with almost the same configuration as that of the above-mentioned converter (see Japanese Patent Application Publication No. 2000-138950), a decoder for decoding an MPEG (Moving Picture Experts Group) image signal (see Japanese Patent Application publication No. 2000-135356), and so on.
In the above-mentioned converter for converting the NTSC-system video signal into the Hi-vision video signal, an image according to the Hi-vision video signal has a fixed resolution and so cannot have a desired resolution corresponding to the image contents, unlike the conventional adjustment of contrast, sharpness, etc.
Each prior apparatus as described above can process only one function at a time and so are not efficient in operation.